Many pharmaceutical and cosmetic compositions are commercialized in vials made of plastic or glass. The vials are filled at the factory by automated filling equipment. A typical automated filling station includes several modules having different functions. There is a container feeding module that supplies empty vials on a conveyor belt delivering the vials to a filling module dispensing in each vial it predetermined quantity of liquid. A capping module applying caps to the individual vials then closes the vials.
An important consideration when filling vials with pharmaceutical compositions, such as injectables, is the prevention of contamination. Since a filling station will typically be used to dispense a wide range of different products it is important to thoroughly clean the station from one production run to another. The cleaning operation is time-consuming because it requires disassembling the various components of the machine that are in contact with the dispensed liquid. In addition to the disassembly operation, the components need to be totally cleaned and sterilized before put back together for a subsequent production run.
One of the most difficult components to clean is the pump used for dispensing the liquid. Pumps that use reciprocating pistons require complete disassembly of the pumping chamber including removal of all seals to expose all surfaces that may have come into contact with the liquid.
To facilitate the cleaning operation the industry is now accusing peristaltic pumps in which the dispensed liquid is contained in a flexible conduit and never comes in contact with the components of the pump that perform the liquid expulsion into the vials. When a production run is completed and the machine is prepared for a new production run it suffices to replace the flexible tubing through which the liquid has been dispensed with a new one.
With such pump design, the cleaning of the filling station can be made much more quickly, which saves time and ultimately increases the productivity since the machine down time is reduced.
A typical peristaltic pump has a pump body defining a cavity in which is placed a rotor. The conduit made of flexible material through which the liquid circulates is placed between the rotor and the pump body. Lobes on the rotor engage the flexible tube and constrict it. As the rotor turns, the constrictions trap a certain amount of liquid in the tube and displace it, thus producing a pumping action.
When a production run on a filling station that uses a peristaltic pump is completed, the flexible tubing is discarded and replaced by new tubing, which may need to be of different diameter. To allow the pump to operate with a different tube size, a holder is required which is designed for that particular tube size. The operator, therefore, needs to remove from the pump the holder for the previous tube size and replace it with a holder for the tube size that will now be used.
This operation may sometimes be overlooked with the result that the pump may be put back in operation with the improper tube holder. This may result in situations where the flexible conduit is no longer held adequately in the pump body and may move as the lobes of the rotor engage the tube.
For a peristaltic pump to dispense with precision a preset quantity of liquid the flexible tube must be held stationary with relation to the pump body. This is especially true when the individual doses that are delivered in the vials are small, in the order of a couple of cubic centimeters. Any relative movement of the tube with relation to the pump body is likely to change the quantity of liquid delivered, such that there will be a variation in the amount of liquid that is actually dispensed from the nominal quantity the vial should be holding.
From that perspective, there is a need in the industry to provide an improved peristaltic pump allowing performing tube changeover operations with reduced risk of wrongly setting the pump for a new production run.